(1) Field of the Invention
This invention relates to the treatment of bodies of water such as lakes with various treatment agents to improve the quality of the water. More particularly, the invention relates to the accurate application of chemical and other agents to bodies of water by the use of floating platforms such as boats and the like. More particularly still, the invention provides an apparatus and method for applying the treatment agent on a uniform and effective basis designed to overcome or mitigate undesirable chemical conditions or balances in bodies of water. The invention involves concurrent detection of parameters by which the volume of water to be treated is determined and application of the treatment agent is controlled.
(2) Description of the Prior Art
In recent years, problems of lake acidification resulting largely from so-called "acid rain" have become increasingly serious. While such acidification problems are not new and a variety of techniques have been employed in the past to counteract the adverse effects of excess concentrations of acid in lakes and other bodies of water, the problem in recent years has become particularly acute in the industrialized nations. This is due in large part, it is believed, to the increasing use of combustion processes, and particularly those combustion processes which use high sulfur fuel. Coal and oil, which are ultimately derived from biological residues, frequently contain fairly high levels of sulfur derived not only from the original biological material, but in addition to sulfur brought in from various sources and especially by perculating sulfur compound laden water. Such sulfur compounds are oxidized when the fuel is burned and the sulfur oxides generated pass into the atmosphere where they are dispersed, particularly down-wind. Upon subsequent precipitation from the atmosphere, particularly during rain and the like, such sulfur oxides are combined with atmospheric moisture to form sulfurous, sulfuric and other sulfur acids which give rise to multiple detrimental effects, including damage to biological systems, both in the air and in the water, general deterioration of the environment, progressive destruction of man-made structures and the like.
In addition to sulfur compounds which are given off by the burning of fossil fuels, high temperature combusion processes also form the so-called NOX gases, i.e. the various nitrogen oxides including NO, NO.sub.2 and the like, which upon precipitation from the air with moisture in the form of rain, snow and mist also form acid solutions which have detrimental environmental effects. Since precipitation in the form of rain ultimately collects in ground water and natural bodies of water such as lakes and the like, such bodies of water tend to suffer from an increasing content of both sulfur and nitrogen acids with serious detrimental effects upon the flora and fauna of the aquatic environment. While lakes and other bodies of water are normally slowly neutralized by natural proceses, particularly in limestone regions, the continued receipt of acidified precipitation into such lakes and other bodies of water frequently proceeds at a faster rate than the natural neutralization of the acid within such bodies of water. Small degrees of acidification harms aquatic organisms through the inhibition of reproduction and growth, and in more extreme cases, causes almost complete mortality. In addition, the acidification of lakes, streams and other bodies of water increases the soluble aluminum content of the water which is particularly harmful to young fish. The acidification of lakes and other bodies of water, even of a fairly small degree, can also very seriously affect the ecological balance in such bodies of water with serious environmental and economic effects.
The acidification of lakes, streams and other bodies of water, is as noted above, not a new phenomenon. However, it is an increasingly serious phenomenon. In the past, a variety of techniques have been employed to counteract or mitigate the adverse effects of excess concentrations of acid in bodies of water. For example, American farmers may use millions of tons of neutralizing agents every year to counteract the acidity produced by nitrates and sulphates in chemical fertilizers. Furthermore, since the middle of this century, governmental agencies and private groups in the United States have used a variety of neutralization techniques to protect fish production in acid lakes and other aquatic environments. The problem with acid lakes has been particularly severe in the Eastern United States and the Scandanavian Peninsula in Europe. The reason for the particular problem in both these areas is the fact that they receive prevailing winds from other industrialized areas and a considerable amount of precipitation, all of which tends to remove acid components which have entered the atmosphere in other regions from both industrial and transportation combustion processes used in such regions. Since, as indicated above, acidified waters tend to collect in lakes, unless there is a continuous neutralization of such waters, the lakes tend to become increasingly acidified, often to the point where not only native plants and fish are killed, but essentially all but very specialized organisms are very adversely affected, if not completely destroyed.
While a large proportion of the acid lake problem is due to so-called acid rain, as explained above, other industrial and agricultural practices also add to the acid lake problem. For example, nitrogen and sulfur containing fertilizers may leach into the ground water or run off into natural bodies of water resulting in detrimental acidification of such bodies and poisoning of desirable organisms. Sulfur acids may also form in coal seams which have been opened and exposed to the atmosphere as well as water from various sources and may also be formed from the iron pyrites or iron sulfur compounds in waste coal or culm piles and then leached into surface and ground waters.
One method of counteracting the acid rain and acid lake problems is by neutralization of the affected lakes and other bodies of water by various neutralizing agents. Rehabilitation of surface waters has been experimentally practiced with a number of reagents, including lye, sodium carbonate, calcitic and dolomitic limestones, hydrated lime, quicklime and slurried industrial slags, which are essentially calcitic or dolomitic lime material. Calcitic limestone has proved for a number of reasons to be the material of choice, particularly since it is readily available and relatively cheap. Calcitic limestone is comprised primarily of calcium carbonate and is a natural solution component of many lakes and streams where it acts as a buffering agent. Calcitic limestone also has a moderate reactivity which protects fish against so called pH shock. It may also be relatively easily prepared in slurries or solutions applicable to a variety of acidic conditions.
Slurries and solutions of calcitic limestone, usually in the form of a slurry, have been applied to lakes and other bodies of water by means of boats and by helicopters, usually by spraying the slurry from a hose into the body of water. Normally the pH of the body of water is first established and the volume of water in such body is at least roughly estimated or determined, after which the amount of calcium slurry necessary for application to the body of water in order to neutralize the acid content of the water is calculated. Refinements of the basic neutralizing agent application process have included division of a body of water arbitrarily into a number zones and measurement of the depth of the water in each of such zones whereupon an amount of neutralization agent may be applied to each zone calculated to effect the desired raising of the pH of the water in such zone. The pH reading, of course, is a measure of the hydrogen ion content of the water. A further refinement has been the use of coarser particles of calcitic material in a limestone slurry to penetrate deeper portions of a lake or other body of water. The larger particles resist complete dissolution in the water before they reach the bottom.
It can be readily seen from the description above that the liming or neutralization of an acid lake is no small undertaking. The neutralization agent cannot be applied heedlessly to such body of water because of the cost and since the production of too basic an environment in the water may frequently be almost as harmful to aquatic life as too acid an environment. In fact, the so-called eutrophication of lakes by excessive contents of phosphates and other growth-accellerating ingredients may be accentuated by overliming of such bodies of water. Furthermore, while limestone particles which settle to the bottom of the average lake tend to sink into the bottom mud or ooze and are thus effectively removed from further affecting the basicity of the overlying water, excessive bottom limestone is thought to adversely affect adjacent aquatic plant life.
It is also undesirable to have zones of different acidity or pH in a lake, since aquatic life traveling from one zone to another may be deleteriously affected. Fish especially, and game fish, in particular, tend to be adversely affected by so-called pH shock engendered by quick changes in the pH of their environment. Zoning and stratification of pH zones in lakes is often accentuated by the slow mixing of the waters of such lakes. Consequently, it has been found very difficult to effect a uniform and accurate liming of bodies of water by the equipment and techniques heretofore used. This has been so, in spite of the fact that very great care is taken in the liming of lakes to try to obtain a uniform application of the liming or neutralization material, i.e. the aim is to apply a uniform amount of material to a uniform volume of water. In most cases, this has been done by first drawing up a topographical map of the lake to be treated using soundings or measurements of the depth of the lake taken in many places throughout such lake. A grid is then placed over this map and the lake is divided into zones based on the average depth of such zones. From this topographical map, the volume of the water in such zones is calculated. Next, the amount of material required for each zone for neutralization of the water in such zone is determined from the volume of water, the acidity measurements of the lake, and the neutralization value of the chemical which is to be applied to the lake. The neutralization material is then applied to the lake waters, usually from a boat or a helicopter in conformance with, or as much in conformance with as is possible, these predetermined calculations.
In actual practice, the treatment zones are usually marked in the lake by placing buoys at stratigic boundries thereabout, whereupon each zone can be treated with the precalculated amount of material. A slurry of neutralization agent in which the particles are of approximately the size which will dissolve completely as they settle from the surface to the bottom of the lake is then prepared. If the water, however, turns out to be deeper than expected, the particles may dissolve before they reach the bottom, leaving a bottom volume which has not been neutralized. Since bottom water in a lake very often is either not changed or infrequently changed by mixing, this unneutralized portion may persist for many weeks or even months. On the other hand, if the size of the particles of the slurry are too large for the depth of the water, such particles may not dissolve by the time they reach the bottom of the lake, but will settle onto the bottom and either be lost in the bottom debris or mud or form an over-neutralized zone along the bottom. This over-neutralized zone will also tend to persist over long periods due to non-mixing of the bottom waters.
It is an object of this invention, therefore, to provide a method of applying treatment materials such as neutralization materials to a lake or other body of water in a more accurate manner than could heretofore be accomplished.
It is a further object of the present invention, to provide a method of applying a treatment agent such as a neutralization agent to a lake or the like in accordance with a simultaneously calculated plan of application.
It is a still further object of this invention to provide an apparatus arrangement which may apply a carefully controlled and simultaneously calculated amount of treatment agent such as neutralization agent to a lake or other body of water.
It is a still further object of this invention to provide an apparatus assembly which is especially and appropriately adapted to the application of a slurry of calcitic limestone to a body of water in an accurately measured, expeditious and efficient manner by a readily portable application apparatus.
Other objects and advantages of the invention will become evident upon review of the following description and explanation of the invention in conjunction with the appended drawings.